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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 | 1x 1x 7x 7x 7x 7x 7x 7x 1x 14x 7x 1x 6x 3x 1x 1x 1x 12x 6x 5x 1x 6x 6x 6x 6x 1x 4x 2x 2x 2x 2x 2x 13x 13x 6x 7x 13x 1x 4x 2x 1x | import { $$asyncIterator } from 'iterall';
import { PubSubEngine } from 'graphql-subscriptions';
/**
* A class for digesting PubSubEngine events via the new AsyncIterator interface.
* This implementation is a generic version of the one located at
* https://github.com/apollographql/graphql-subscriptions/blob/master/src/event-emitter-to-async-iterator.ts
* @class
*
* @constructor
*
* @property pullQueue @type {Function[]}
* A queue of resolve functions waiting for an incoming event which has not yet arrived.
* This queue expands as next() calls are made without PubSubEngine events occurring in between.
*
* @property pushQueue @type {any[]}
* A queue of PubSubEngine events waiting for next() calls to be made.
* This queue expands as PubSubEngine events arrice without next() calls occurring in between.
*
* @property eventsArray @type {string[]}
* An array of PubSubEngine event names which this PubSubAsyncIterator should watch.
*
* @property allSubscribed @type {Promise<number[]>}
* A promise of a list of all subscription ids to the passed PubSubEngine.
*
* @property listening @type {boolean}
* Whether or not the PubSubAsynIterator is in listening mode (responding to incoming PubSubEngine events and next() calls).
* Listening begins as true and turns to false once the return method is called.
*
* @property pubsub @type {PubSubEngine}
* The PubSubEngine whose events will be observed.
*/
export class PubSubAsyncIterator<T> implements AsyncIterator<T> {
constructor(pubsub: PubSubEngine, eventNames: string | string[], options?: unknown) {
this.pubsub = pubsub;
this.options = options;
this.pullQueue = [];
this.pushQueue = [];
this.listening = true;
this.eventsArray = typeof eventNames === 'string' ? [eventNames] : eventNames;
}
public async next() {
await this.subscribeAll();
return this.listening ? this.pullValue() : this.return();
}
public async return(): Promise<{ value: unknown, done: true }> {
await this.emptyQueue();
return { value: undefined, done: true };
}
public async throw(error): Promise<never> {
await this.emptyQueue();
return Promise.reject(error);
}
public [$$asyncIterator]() {
return this;
}
private pullQueue: Array<(data: { value: unknown, done: boolean }) => void>;
private pushQueue: any[];
private eventsArray: string[];
private subscriptionIds: Promise<number[]> | undefined;
private listening: boolean;
private pubsub: PubSubEngine;
private options: unknown;
private async pushValue(event) {
await this.subscribeAll();
if (this.pullQueue.length !== 0) {
this.pullQueue.shift()({ value: event, done: false });
} else {
this.pushQueue.push(event);
}
}
private pullValue(): Promise<IteratorResult<any>> {
return new Promise(resolve => {
Iif (this.pushQueue.length !== 0) {
resolve({ value: this.pushQueue.shift(), done: false });
} else {
this.pullQueue.push(resolve);
}
});
}
private async emptyQueue() {
if (this.listening) {
this.listening = false;
if (Ithis.subscriptionIds) this.unsubscribeAll(await this.subscriptionIds);
this.pullQueue.forEach(resolve => resolve({ value: undefined, done: true }));
this.pullQueue.length = 0;
this.pushQueue.length = 0;
}
}
private subscribeAll() {
if (!this.subscriptionIds) {
this.subscriptionIds = Promise.all(this.eventsArray.map(
eventName => this.pubsub.subscribe(eventName, this.pushValue.bind(this), this.options),
));
}
return this.subscriptionIds;
}
private unsubscribeAll(subscriptionIds: number[]) {
for (const subscriptionId of subscriptionIds) {
this.pubsub.unsubscribe(subscriptionId);
}
}
}
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